[E. Margaret Burbidge is director of the Center for Astrophysic
and Space Sciences. University of California at San Diego. La
Jolla 92093. This article is adapted from the text of the presidential
lecture at the AAAS annual meeting on 29 May 1983 in Detroit.
Michigan]

Summary: The exploration of the universe ha
captured mankind's interest since the earliest attempts to understand
the sun, moon, planets, comets, and stars. The last few decade
have seen explosive advances of knowledge, sparked by technological
advances and by our entry into the space age. Achievements in
solar system exploration, discoveries both in the Milky Way and
in the farther universe, and challenges for the future are discussed.
Of major concern worldwide is the need for people of goodwill
in all nations to concentrate on the peaceful uses of outer space
and on international collaboration.

I have chosen the subject of the adventure into space for two
reasons other than its appeal to me as an astronomer. One is a
recognition of a basic drive of human beings to find out about
the world we live in. This is an inborn urge, as is well known
to anyone who has watched a baby explore the expanding reachable
world of toes and fingers, crib, living-room floor, and backyard.
What is more natural than to look toward an ultimate goal-exploration
of the entire universe, even though mostly by reasoned analysi
of the data, since the far universe is indeed almost incomprehensibly
far.

The synergistic and dramatic recent advances in high technology
and our entry into the space age have produced a ferment of excitement
in the once-quiet field of astronomy. The pot is kept bubbling
by a flow of new concepts, new ideas, and above all, new observations,
leading to discoveries which are sufficiently exciting to capture
everyone's interest. The large number of new descriptive astronomy
books aimed at the general reader, in addition to best-selling
fictional books on space ventures, must bear witness to this arousal
of public interest. Of course, most of the astronomy books are
enhanced by many beautiful pictures because astronomy is a science
of visualization as well as analysis and theory.

There is a dark reverse side to the coin, however, and that i
the same technological advances have given us the capability of
extinguishing life on Earth in a nuclear holocaust, or of smothering
it in waste. That is my second reason for choosing this topic.
I shall return to it later .

Exploring the Solar System

With all the frontiers on the earth broached, the next frontier
for exploration is above the earth's surface-the frontier with
the rest of our solar system. And here I have to point out that
exploring this frontier is an expensive operation. My favorite
commentary on this is given by a B.C. cartoon [by Hart] that appeared
several years ago, in which the conversation ran as follows:

"The secrets of all creation, secrets that could mean the
salvation of mankind, are locked in those stars."

"Gosh !"

" Why can't we reach out and unlock those secrets?"

"The keys are not ours to have."

"How come?"

"It ain't in the budget!"

However costly, though, the budgets for the exciting venture
of the past two decades, and those planned for the remainder of
this century, are but a tiny fraction of the U.S. military budget-some
three to four times 103 for fiscal year 1984 (1,
2). Also, the expenditures during the past 20 years have pushed
technology in many useful fields, especially the development and
miniaturization of computers and instruments, advances in the
science of communications, and the flow of data from the Landsat
and weather satellites. The most expensive ventures are obviously
those involving manned space flight. Yet those who watched on
television the Apollo 11 landing on the moon will never forget
the thrill of seeing those first steps by astronauts Aldrin and
Armstrong. For myself, I cannot look at the moon at night without
thinking "We have been there," and without reflecting
regretfully that, had I been born one or two centuries later,
I might have been able to step in those footprints.

The Apollo mission was mainly one of exploration. Only a small
part of the lunar surface was explored: nevertheless, some intriguing
results were obtained, especially concerning the moon's seismology
and the chemical and isotopic composition of a small part of the
surface material, enough to give a tantalizing glimpse into the
past history of the solar system (3).

Going farther out into the solar system, to the nearest large
bodies beyond the moon, we pass beyond today's goal for manned
space flight, into the realm where carefully designed and constructed
unmanned space vehicles can reveal as much information about Mars,
Venus, and Mercury as we have about the moon. Mariner 10 showed
that Mercury has a surface like the moon's, cratered by meteoritic
bombardment. Close as it is to the sun, where it receives a heavy
dose of solar wind charged particles, it has a magnetosphere in
which Mariner 10 observed intermittent intense bursts of high-energy
particles. The U.S.S.R. Venera landers on Venus and the U.S. Mariner
and Pioneer flybys have shown that the hot, enormously dense and
dynamic atmosphere of Venus has huge quantities of CO2,
very little water, and is topped by clouds of sulfuric acid. It
is indeed an inhospitable place for manned exploration. The little
of Venus's surface topography that has been unveiled shows past
volcanic activity and whets the appetite for more detailed knowledge.
A proposed Venus Orbiting Imaging Radar has had to be shelved
because, to quote B.C. again, "It ain't in the budget,"
but a Venus Radar Mapper of reduced scope, without an atmospheric
probe, is planned for 1988 (4).

The least inhospitable of our neighboring planets is Mars, and
NASA's Viking lander showed unweathered craters produced by past
meteoritic bombardment, like those on the moon and Mercury, yet
also showed dry river channels, suggesting the flow of water or
some other liquid in the past. Again, the preliminary studie
of the geography and climatology of Mars are the incentive for
more detailed study by orbiters planned by NASA for the 1990's.

Perhaps the most spectacular planetary studies have been those
made by Voyager 1 and Voyager 2, flying around and past Jupiter
and Saturn, their satellites, and Saturn's fantastic ring system.
These have been triumphs of planning and technological skill,
in the accuracy of placings of the Voyagers and the superb operation
of their communications systems. And there is more to come when
the space odyssey reaches Uranus, twice as far out as Saturn.
The variety displayed by Jupiter's and Saturn s satellites (5)
again gives tantalizing hints about the early history of the solar
system. Here again, heavy bombardment by meteorites occurred in
the past, while Saturn's largest satellite, Titan, is unique in
having a thick atmosphere-mostly nitrogen, some methane, possibly
argon, some simple organic molecules, and also atmospheric aerosol
that may be more complex organic molecules (6). Active
volcanoes on the innermost large Jovian satellite, Io, were a
surprise indeed. Once again, the planned return to Jupiter with
NASA's satellite Galileo has been scaled down because of current
budgetary considerations, but one can further into the future
and aim for flyby and probe investigations of Jupiter, Titan,
Saturn, Uranus, and eventually Neptune (4). How exciting
it would be to discover what is at the 'bottom ' of the Great
Red Spot on Jupiter that enables this weather system to persist
for hundreds of years (7).

The planets and their satellites by no means comprise all the
objects of interest in the solar system. The smaller components-asteroid
and comets-are candidates for intensive study by satellites that
actually make rendezvous with them. The asteroids-solar system
debris-are conceivably useful sources of raw materials (8).
(I return to this possibility later.) In any case, chemical, spectroscopic,
and isotopic analysis of more than one asteroid will yield interesting
data on their origin, their place in the history of the solar
system, and their possible use in the eventual colonization of
space.

Because of the fear and awe they have inspired in primitive and
prehistoric peoples, and indeed also in more recent centuries,
comets hare always been objects of intense interest and study.
They continually surprise us: while people were thinking and writing
about the famous Halley's comet, due to reappear in 1985 and already
detected at Palomar Observatory as a very faint object, and while
we were deploring the fact that NASA was unable to include a dedicated
comet mission in its budget, there appeared in the May skies an
unpredicted comet that passed very close to the earth. It is the
first comet whose name includes that of a space satellite-Comet
IRAS-Araki-Alcock-because the Infrared Astronomy Satellite IRAS
(9) made the first observation of it.

Comets can be quite diverse. The beautiful 1976 Comet West passed
close to the sun and developed a spectacular tail, while Comet
IRAS, which passed close to the earth but not to the sun, wa
bright, fuzzy, but without much of a tail. Aside from the known
periodic comets, there may be many that start sunward from a "cloud"
far beyond the orbit of Pluto. Whether some comets provide a sample
of truly interstellar matter is still an open question.

Beyond discovery and exploration, the ultimate goal of studie
of the solar system is to unravel the secrets of its origin and
early history, and to learn whether planetary systems around sunlike
stars are common or rare.

Beyond the Solar System

I turn now to the realms beyond the solar system-the farther universe,
including fields studied in my own research. This kind of voyage
of discovery cannot be made through direct exploration but must
be carried out through the synthesis of data received on the earth
by state-of-the-art and future instrumentation on telescopes covering
the entire electromagnetic spectrum, both from satellites in earth
orbit and from the ground .

Astronomers are accustomed to planning far ahead both in the research
programs to be tackled and in the instruments with which to carry
out the research. For example, the Space Telescope (10, 11)
with its 2.4-meter mirror, to be launched in 1986 by the Shuttle,
has been decades in the planning. In orbit above the earth's atmosphere,
it will reveal the ultraviolet spectrum of objects from our nearest
neighbors to the most distant galaxies and quasars, and with a
spatial resolution better than ten times that achieved with ground-based
telescopes.

The long-term nature of astronomical research and the fact that
we are always scrounging for that last little photon and the utmost
improvement in signal-to-noise ratio that our instruments will
yield have been drivers toward international cooperation. Science
is done jointly by the United States, the U.S.S.R., Europe, Canada,
South America, Mexico, Australia, Japan, and South Africa. Expensive
space programs are particularly suitable for international cooperation,
and very long lead times are needed in their planning.

The report of the Astronomy Survey Committee to the National Academy
of Sciences (12) is such a planning document. It present
an in-depth account of the current state of knowledge about the
universe and of the spearheads for advancing that knowledge and
understanding. It recommends a set of programs that the committee
judged to be priorities for the 1980's, and proposes the instrument
with which to carry out these programs. Its final chapter look
further ahead and discusses planning for programs that have exceptional
promise for the 1990's and beyond. To take a brief look at some
of those goals and plans, let us move out of the solar system,
into the realm of the Milky Way, our home galaxy.

During the past 30 years the physical properties of stars during
the main part of their lifetimes have become quite well understood,
from a combination of theory with observations of the energy outputs,
surface temperatures, chemical compositions, and masses of a great
variety of stars at different evolutionary stages. The least well
understood stages, about which we would like to know more, are
the beginning and end phases.

Throughout most of their existence, stars function well as self-regulating
thermonuclear fusion reactors, such as our sun. Trouble come
when the nuclear fuel (first hydrogen, then helium, carbon, and
so on) begins to be exhausted and the star can no longer maintain
its balance between pressure and gravity by a constant generation
of energy in its interior. Such a star can die quietly, shedding
its outer layers and contracting its core, and eventually becoming
an extremely dense white dwarf that continues to radiate by cooling.
The well-known planetary nebula in Lyra, the Ring Nebula, is an
example of a star in this process. Or a star can die in a catastrophic
collapse-implosion, followed by explosion, as a supernova. Such
an event in A.D. 1054 was documented by ancient Chinese astronomers,
who saw a star that became so bright that for some weeks it could
be seen in the daytime. It has left us the expanding remnant of
the explosion, the Crab Nebula-perhaps the most interesting object
in the sky. When radio astronomy was a young science, in the 1940's,
the Crab was one of the first astronomical radio sources to be
detected. The origin of the radio waves was understood to be radiation
by high-energy charged particles accelerated in magnetic fields.

This was not all the radio astronomers discovered about violent
star death. With technical improvements and a capability for high
time resolution, they discovered that one of the central star
in the nebula is not shining constantly but is emitting spurt
of radiation 30 times a second (13). This central object
must be the remnant of the imploded original stellar core, crushed
into matter of extremely high-in fact, nuclear-density, so that
it forms a neutron star. Conservation of angular momentum cause
this object, whose radius is only some 15 kilometers, to rotate
with a 30-millisecond period. The enormous compressed magnetic
field and its interaction with charged particles from the surface
produces a beam of radiation that sweeps past the earth 30 time
a second.

Given the period, optical astronomers could look and see the same
beaming in visible light (14). But the Crab has even more
wonders to offer. It was recognized by an ingenious early rocket
experiment to be a source of diffuse x-radiation (15).
A point x-ray source at the center was discovered to be an x-ray
pulsar, and the HEAO 2 (Einstein) satellite has produced beautiful
images of it in its "on" and "off" phase
(16). The neutron star is thus a radio, optical, and x-ray
pulsar.

Radio astronomy and optical astronomy can continue through the
next several decades from the ground, but x-ray astronomy need
a satellite because observations must be made from above the earth'
atmosphere . Consequently, an Advanced X-ray Astrophysics Facility
(AXAF) for imaging and spectroscopic work is a first-priority
goal. AXAF is planned to have a sensitivity up to 100 times greater
than that of any previous x-ray mission. It will extend the revelation
of the Einstein satellite, which showed the sky to be peppered
with x-ray sources-single and double stars in the Milky Way, remnant
of old supernovae, and, outside the Milky Way, active galaxies,
quasars, and diffuse hot material in clusters of galaxies, reaching
to the bounds of the observable universe.

I cannot leave the subject of x-ray astronomy without a few word
about an amazing and, so far, unique x-ray object known as SS
433. Appearing as a 14th magnitude star at the position of an
x-ray source, it had already been cataloged as unusual in having
strong emission lines in its spectrum. Intensive study by B. Margon
and many others showed it to have the extraordinary property described
by the news media as "coming and going at the same time"
(17, 18), A graph of velocities measured from the Doppler
shift of its spectral lines looks like that of any ordinary double
star until one reads the figures on the velocity axis, which show
a total range of 85,000 kilometers per second or about a quarter
of the velocity of light. A preliminary and a later artist's conception
of what is going on, shown in the two popular review article
(17, /8). indicated a double star, one of which has collapsed
and is sucking material off its companion. The infalling material
is heated to x-ray-emitting temperatures, and the collapsed object,
rotating about a precessing axis inclined to the axis of the orbital
plane of the pair of stars, squirts out jets of matter in opposite
directions, which are seen by us as the material "coming
and going at the same time."

I now turn to that other little-understood part of a star's life
history-its formation. This is, of course, very relevant to our
attempts to decipher the formation and early history of the solar
system and to the question of whether planetary systems about
stars are common or rare. It is known that massive hot stars are
short-lived in comparison to stars like our sun, which is some
5 billion years old and only halfway through its main sequence
lifetime. Thus, it has long been recognized that stars are continually
forming in the Milky Way (and in other similar galaxies). The
well-known Orion Nebula is one such region of recent star formation:
young stars are embedded in a vast complex of hot and cold ga
and dense molecular clouds and clouds of dust. The Lagoon Nebula
in Sagittarius is another such region.

The best instruments for penetrating the shielding clouds of dust
are those that detect infrared radiation, and recent technology
has produced many such telescopes, which are used on high mountain
and in airplanes so that they can be above much of the water vapor
that obscures the infrared. These instruments are providing a
wealth of information, both on new stars in the process of formation
and on old stars beginning to shed their outer material in cloud
of dust. A composite infrared picture of the Orion Nebula made
from the Kuiper Airborne Observatory (4) shows such protostar
coalescing out of the nebula's gases. The most recent observatory
at work is the IRAS, to which I referred earlier as the discoverer
of a comet. This is a truly international, and highly successful,
satellite that is now mapping the heavens for infrared sources,
as the Einstein satellite did for x-ray sources.

Detailed study of the infrared sources detected by IRAS (both
within and outside the Milky Way) will be carried out by instrument
planned for the future: among them are a Shuttle Infrared Telescope
Facility and a Large Deployable Reflector (9, 12).

Let us move beyond the confines of the Milky Way. Among external
galaxies, there are some which are intense sources of radio radiation.
The activity that produces the high-energy charged particles necessary
to emit radio radiation originates in the central nucleus of the
galaxy. The high-energy particles are usually beamed out in two
opposite jets, into what become two radio lobes well outside the
visible galaxy. As calculated many years ago by G. Burbidge (19),
the particle and magnetic field energies demand the release of
a huge quantity of energy in the central region-as much as the
rest-mass energy of 108 solar masses in some cases.
The beaming mechanism may work like an enormously scaled-up version
of what goes on in SS 433. It is sometimes remarkably constant
in direction, as in the radio galaxy NGC 6251 (20). In
other cases, the direction shifts, perhaps because of interaction
of the particles with an extragalactic medium.

I have said nothing yet of the radio telescopes that obtain such
detailed maps. The large-scale, high-resolution observations of
NGC 6251 were made with the National Science Foundation's Very
Large Array at the National Radio Astronomy Observatory, a set
of 27 dishes that move on Y-shaped tracks with a fullest extent
of some 30 kilometers. The full array can produce resolution
better than the best ground-based optical telescopes. Color-coded
pictures of several cosmic jets, emanating from radio galaxies,
may be seen in a descriptive article by Blandford et al.
(21).

To improve resolving power still further, radio astronomers have
developed very long baseline interferometry (VLBI), in which signal
from radio dishes spaced at intercontinental distances are combined
in the computer. This produces a resolution 1000 times higher
than the best optical ones, and a proposed extension and upgrading
of the system-a Very Long Baseline Array-will do still better.
This type of operation is truly international because, in carrying
out an observational sequence with VLBI, data from the United
States, Canada, Europe, and the U.S.S.R. are combined: this involve
collaboration of scientists at all these telescope sites.

Radio, microwave, infrared, x-ray-these data could not be deciphered
without the all-important optical telescopes. Here again, we pin
our hopes for better understanding these objects and for making
new discoveries on future instruments. The Space Telescope will
reveal the ultraviolet and will give us far sharper pictures than
we can get from the ground today. But it is limited in size; it
mirror is only 2.4 meters in diameter. Optical astronomers are
therefore planning new very large telescopes on the ground, to
work in conjunction with the space instruments. An engineering
group at Kitt Peak National Observatory, under the direction of
KPNO Director Geoffrey Burbidge, has constructed models for two
concepts of a future National New Technology Telescope under study
by the National Science Foundation. Such a telescope, with an
effective mirror diameter of about 15 meters, dwarfs the model
on the same scale of the largest existing national telescope,
the Kitt Peak 4-meter telescope.

I was describing cosmic activity in external galaxies and cannot
end without a few words about two of my favorite objects, in which
it seems that bullet-like lumps of plasma are shot out of the
nuclei of galaxies. The first is well known and was one of the
earliest radio sources to be detected (22). It is a galaxy
known as M87. A seemingly ordinary spherical conglomeration of
stars, if one looks at a strongly exposed photograph, it is found
to be much more interesting when looked at visually through a
large telescope. A blue jet thrusts out from the center, strikingly
outlined against the yellowish stars of the galaxy. A short exposure
photograph in visible light shows this jet; it turns out to be
a stream of blobs containing high-energy charged particles in
a magnetic field. M87 is also a strong x-ray source-another astronomical
wonder that provides something for everyone. The second object
is a radio galaxy, perhaps akin to M87, which is emitting plasma
blobs in a jet and apparently producing an extensive and complex
additional radio source that encompasses a quasar and ultraviolet
objects, whose nature a group of us are trying to decipher (23).

The Earth

This section brings me back to that dark side of the coin to which
I referred at the beginning, my second reason for choosing thi
topic. However, it also enables me to look into the future and
to say something about the possibility of constructing giant space
colonies to which adventurous human beings may travel and in which
they may live comfortably.

In the early 1960's the first pictures of the earth as seen from
outside were obtained from the Apollo flights, and Rachel Carson'
book Silent Spring (24) was published. The Apollo
pictures brought home, as nothing else could, the fact that we
inhabit a bounded surface, in an environment which we can cherish
or violate and which is home to an ever-growing human population
whose ever increasing waste products it must house. Carson's book
focused on toxic waste products and the havoc they can cause to
all life on the earth. It was written after our entry into the
nuclear age, but before the proliferation of nuclear weaponry
in several continents and the problem of nuclear waste disposal.
Its main concern was chemical toxic wastes, but the problem of
radioactive fallout from atmospheric testing of nuclear bomb
was also addressed. In dedicating the book to Albert Schweitzer,
Carson quoted him as saying, "Man has lost the capacity to
foresee and to forestall. He will end by destroying the earth."

A positive action was taken in 1963, the year after the publication
of Silent Spring: President Kennedy delivered his famou
speech at American University in which he announced the end of
nuclear tests in the earth's atmosphere and laid the groundwork
for the test ban treaty and the first nuclear arms limitation
agreement. The speech was one of the highlights of his career.

The cessation of nuclear bomb testing in the atmosphere and in
space outside the earth has not, however, lessened the accumulation
during the past two decades of nuclear waste from military nuclear
activities, and it is this problem which I want to address now.
In preparing this section I have been helped and advised by two
of my colleagues, Hannes Alfvén and Robert B. Livingston,
and I thank them for the material and references they provided.

Alfvén pointed out the physical impracticality of an early
idea of mine, that nuclear waste materials could be loaded into
sun-bound satellites and fired off into the sun's atmosphere,
where they would be harmlessly absorbed into its massive hot interior.
He pointed out that elementary celestial mechanics shows the impossibility,
energywise, of such a project. So, if we must find ways to dispose
of nuclear waste within the confines of the earth itself, how
will this important problem be tackled?

It is heartening to see the growing awareness on the part of scientists,
politicians, and the public of the acuteness of the problem. It
is, of course, linked with the sword of Damocles hanging over
the world-the threat of nuclear war. The attention being given
by AAAS to all aspects of the problem is demonstrated by the number
of symposia devoted to it at the 1983 Annual Meeting and by the
continuing concern of its committees and council. Also, many thoughtful
books and articles have appeared, among which I would like to
draw attention to papers by Alfvén (25) and Lester
(26) and to a book by Shapiro (27). In his foreword,
Shapiro recalls an experience in high school when the teacher
asked the class what their first step would be if they were assigned
the task of producing "an acid so powerful it would dissolve
any substance." None of the students gave the correct response,
which was "Suppose you ever got such an acid . . . what could
you keep it in? The first thing you have to determine in any experiment
is, when you get whatever it is you're going after, what are you
going to keep it in?" Shapiro gives the quantities and location
of various radioactive waste materials, the half-lives of the
dangerous radioactive species, and the estimated costs for safe
disposal.

I turn now to the threat of nuclear war, which grows as the arm
buildup grows and as new nations enter the nuclear arena, and
which can be averted only by a dedicated effort toward international
communication and cooperation. It is time for all responsible
people to realize the impossibility of "limited nuclear war."
It was shocking to discover that there were those who could contemplate
the aftermath of a nuclear war with 20 million humans killed in
the United States. Astronomers are used to large numbers and to
attempting to depict them to nonastronomers. Such a toll of bodies,
at an average height of 5 1/2 feet per person, would form a line
stretching around more than eight-tenths of the equatorial circumference
of the earth. I must believe that men and women of good will have
reached a consensus that nuclear holocaust must he avoided.

The consequences of such a disaster have, of course, been explored
in fiction. Aldous Huxley, in Ape and Essence (28)
wrote of the discovery of a movie script set in the year 2108,
in which a group of men and women embark from New Zealand on a
"rediscovery expedition to North America" following
their isolation from the Northern Hemisphere for more than a century.
The Northern Hemisphere had been devastated but not totally depopulated
by a third world war, and Huxley imagined a remnant of human survivors,
totally brutalized and suffering from grotesque genetic mutation
caused by nuclear irradiation. Nevil Shute, in On Tale Beach
(29), also wrote of the aftermath of a nuclear war in the
Northern Hemisphere. Australia was again spared temporarily because
of the separate wind circulations in the two hemispheres. An expeditionary
group set out to investigate what seemed to be a coherent message
being tapped out somewhere in North America. They discovered a
total absence of life: the "message' was the random tapping
of an electric cable blowing in the wind. Shute's book ends on
a far more pessimistic note than Huxley's, with the extinction
of life all over the earth.

Before leaving this somber subject and turning to positive goal
for the future, I must comment on the thoughts of several scientist
interested in the question of whether intelligent life exist
elsewhere in the universe. I have briefly discussed the birth
of new stars in the Milky Way, and it is widely recognized that
there may be stars in the solar neighborhood which have planetary
systems like ours. Indeed, it is hoped that the Space Telescope
can devote time to investigating these nearby stars for dark,
planet-sized companions. As advances in microwave and infrared
technology reveal the existence of more and more complex organic
molecules in dense interstellar clouds which are likely site
for new star formation, we can envision a primordial organic mixture
out of which life might have evolved elsewhere than on the earth-in
fact, anywhere having the right environment. Thus, it is worthwhile
to use radio telescopes in a search for signals from outer space.
The Field Committee (12) included a panel on SETI, the search
for extraterrestrial intelligence.

But the speculation that radio signals from extraterrestrial intelligence
might be detected has led to the question: If life is common throughout
the Milky Way, why haven't we already detected it? And that lead
to the further question: For what length of time could living
creatures in another solar system exist, once they had the necessary
technology to send out signals (30, 31)? As several
authors have commented, perhaps the development of highly organized
living creatures is always accompanied by competition, struggle
for scarce resources, and warfare. Acquiring the technology to
send out strong enough radio or microwave transmissions would
presuppose an advanced knowledge of physics, including nuclear
physics and the ability to build nuclear bombs. Perhaps any such
civilization has but 50 years or so (on our time scale) before
it annihilates itself. Should we ask instead whether the development
of a civilization as contentious as ours is an unavoidable consequence
of the possession of "intelligence" and, if so, how
many such civilizations have had the wisdom to pass safely through
the dangerous warfaring phase to an era of cooperation? This i
a task for all of us, and especially scientists, to address, and
we should do so in the belief that we shall succeed. In his 1963
speech at American University (32) after the Cuban missile
crisis, President Kennedy warned that we should not "see
conflict as inevitable, accommodation as impossible and communication
as nothing more than an exchange of threats." He urged: "Let
us focus . . . not on a sudden revolution in human nature but
on a gradual evolution in human institutions.... Peace is a process-a
way of solving problems."

I am going to assume that we will achieve peace and cooperation
and that this will free our resources to face the frontier of
space. Here again I have had the benefit of help, advice, and
material from one of my colleagues, James R. Arnold, and I refer
the reader to his article entitled "The frontier in space"
(8).

The idea of constructing a giant space vehicle in which human
could create a pleasant environment, live their entire lives,
and bring up their families would have sounded like science fiction
50 years ago. So, however, did travel to the moon seem in the
19th century, and we have seen that successfully achieved. We
are seeing now the steady progress of the Soviet Salyut program
and the beginning of the U.S. Space Shuttle program. These and
their future developments will be necessary preliminaries for
embarking on the construction of a very large, perhaps toroidal,
self-contained space colony, perhaps slowly rotating to produce
a gravity-like force to help keep the colonizers comfortable and
healthy. I prefer to envisage this rather than the construction
of military satellites as a goal for both the Salyut and Space
Shuttle programs.

Besides Arnold at the University of California, two physicist
at Princeton University, G. K. O'Neill and Freeman Dyson, have
written and lectured extensively on space colonization. O'Neill
(33) considered the mechanics of mining raw materials from
the asteroids and the moon and using them for the construction
of a vehicle in situ, in earth orbit. Arnold (8) also considered
the chemistry of the materials that would be needed; he discussed
the Apollo data on the compositions of lunar soil samples and
analyses of meteorites that probably indicate the composition
of earth-approaching asteroids. He also discussed the task of
gathering enough solar energy to supply power for separating the
useful elements from asteroids and the lunar soil. Dyson (34)
looked at the costs of such ventures, in a delightful comparison
with the costs of the Plymouth Colony in 1620 and the Brigham
Young expedition in 1847. One should read chapter 11 of Dyson'
book in the belief that, when it is a question of survival or
extinction, human beings of all nations will take the rational
path and demand the replacement of conflict and confrontation
by cooperation and collaboration. Then the enormous worldwide
military expenditures can be directed into constructive channels,
both for improving the quality of life on earth for all and for
tackling the adventure into space.

Conclusion

I have given a quick and selective account of achievements in
space science, the exploration of our solar system, and a look
at future space missions to the planets. I have taken a very brief
and even more selective look at the challenge of the far universe,
where both earth-orbiting telescopes and space instrumentation
and telescopes on the ground will, I hope, take us on the further
road to exploration and discovery in the universe. Costly as these
ventures will be, the estimates for a program for fiscal year
1984 are only a few thousandths of the proposed U.S. military
budget.

I have expressed my hopes for the future, for the replacement
of conflict and confrontation by the start of a truly international
cooperative and collaborative effort which would open up the frontier
with space. This vision of the future is born of my personal interest
in astronomy but is also a recognition of a common human trait-the
desire to explore and to find out about the world. To achieve
such a goal, it is necessary to tackle the multifaceted problem
on the earth, within nations and between nations. In contrast
to the opinion expressed in the quotation from Schweitzer mentioned
earlier, I believe we have the capacity to foresee and forestall.
Scientists of all nations are in a position to forecast the perils,
and can educate and lead in the endeavor to rid the world of nuclear
perils and improve conditions of life for all humans.

I close with a quotation from a 1924 story (35) set in
the early 19th century in the border country between England and
Wales. The narrator is watching a fire burn up the entire corn
harvest at a farm and utters words that express a warning to today'
world: "So it will surely be when the world is burned with
fervent heat in the end of it all. It will go rolling on, maybe,
as it ever has, only it will be no more a kindly thing that mist
about it, a pleasant painted ball with patterns of blue seas and
green mountains upon its roundness. It will be a thing rotten
with fire as an apple is rotten when the wasps have been within,
light and empty and of no account.''

36. I thank many friends and colleagues for help advice, references,
and material, especially J. R. Arnold, R. B. Livingston. H. Alfvén,
C. Sagan, G. Burbidge, G. Field, and R. ordeal. Most of the slide
I showed during my spoken address can be obtained from sets available
from the NASA publications office, Lick Observatory, Kitt Peak
National Observatory, California Institute of Technology, and
Carnage Institution of Washington. Selected sets of solar-system
slides are also available from the Astronomical Society of the
Pacific office in San Francisco.